Covalent Capture of Nitrous Oxide by N‐Heterocyclic Carbenes

Tskhovrebov, Alexander G.; Solari, Euro; Wodrich, Matthew D.; Scopelliti, Rosario; Severin, Kay

doi:10.1002/ange.201106589

Cited by 76 publications

(9 citation statements)

References 46 publications

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“…[43] These results support the conclusion that the [SN = NO] 2À ligand is formed by nucleophilic attack of N 2 Oa tt he sulfide ligand in 4. [39,43,44] In summary,c leavage of the CÀSb ond in [L R Ni(SCPh 3 )] by reductive deprotection provides access to af amily of "masked" terminal Ni II sulfides,[K(L)][(L R )Ni(S)].The NiÀS distances in this class of materials are amongst the shortest observed, suggesting the presence of partial multiple-bond character. [ K(18-crown-6)][(L tBu )Ni(S)] reacts with N 2 Ot o form an ovel thiohyponitrite complex, [K(18-crown-6)]-[L tBu Ni(SN=NO)],c onfirming the lability of the S-K interaction.…”

supporting

confidence: 76%

“…[41,42] Also relevant is the reaction of IPr with N 2 Ot of orm IPr-N 2 O. [43] These results support the conclusion that the [SN = NO] 2À ligand is formed by nucleophilic attack of N 2 Oa tt he sulfide ligand in 4. [39,43,44] In summary,c leavage of the CÀSb ond in [L R Ni(SCPh 3 )] by reductive deprotection provides access to af amily of "masked" terminal Ni II sulfides,[K(L)][(L R )Ni(S)].The NiÀS distances in this class of materials are amongst the shortest observed, suggesting the presence of partial multiple-bond character.…”

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confidence: 55%

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Synthesis of a “Masked” Terminal Nickel(II) Sulfide by Reductive Deprotection and its Reaction with Nitrous Oxide

Hartmann

Hayton

2015

Angewandte Chemie

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The addition of 1 equiv of KSCPh3 to [LRNiCl] (LR={(2,6‐iPr2C6H3)NC(R)}2CH; R=Me, tBu) in C6H6 results in the formation of [LRNi(SCPh3)] (1: R=Me; 2: R=tBu) in good yields. Subsequent reduction of 1 and 2 with 2 equiv of KC8 in cold (−25 °C) Et2O in the presence of 2 equiv of 18‐crown‐6 results in the formation of “masked” terminal NiII sulfides, [K(18‐crown‐6)][LRNi(S)] (3: R=Me; 4: R=tBu), also in good yields. An X‐ray crystallographic analysis of these complexes suggests that they feature partial multiple‐bond character in their NiS linkages. Addition of N2O to a toluene solution of 4 provides [K(18‐crown‐6)][LtBuNi(SNNO)], which features the first example of a thiohyponitrite (κ2‐[SNNO]2−) ligand.

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supporting

confidence: 76%

mentioning

confidence: 55%

Synthesis of a “Masked” Terminal Nickel(II) Sulfide by Reductive Deprotection and its Reaction with Nitrous Oxide

Hartmann

Hayton

2015

Angewandte Chemie

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“…[5][6][7] They have already found numerous applications as highly donating and sterically protecting ligands in organometallic chemistry and catalysis, [8] and are also of high interest in their own right, both as excellent organocatalysts, [9] and also due to their ability to form trappable adducts with (possibly highly reactive) main-group molecules. [10] Most of these widespread applications are essentially exploiting the same reactivity pattern, namely, their strong s-donation and nucleophilicity through the in-plane occupied orbital of the divalent carbon atom (Highest Occupied Molecular Orbital; HOMO). Comparatively, their electrophilicity is weak, just because the vacant p-type orbital of their carbene center (Lowest Unoccupied Molecular Orbital; LUMO) is maintained at high energy by the strong p donation of the two surrounding nitrogen atoms.…”

Section: Introductionmentioning

confidence: 99%

The Ambivalent Chemistry of a Free Anionic N‐Heterocyclic Carbene Decorated with a Malonate Backbone: The Plus of a Negative Charge

César

Labat

Miqueu

et al. 2013

Chemistry A European J

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The anionic heterocycle "[maloNHC](-)", ([1](-)), is the archetype of a growing family of N-heterocyclic carbenes incorporating an anionic backbone; here, a malonate group. A comprehensive experimental exploration of its chemistry as a free entity (in the form of its lithium salt [1]·Li) is presented, and rationalized using DFT calculations at the B3LYP/6-31+G** level of theory. For the sake of comparison, similar computations were performed on other representative carbene types. Reactions of [1]·Li with a broad series of electrophilic reagents were used to ascertain its intrinsic nature as a nucleophilic carbene. Unexpectedly, [1]·Li was also seen to react with the nucleophilic tert-butylisocyanide, to give an anionic ketenimine, which could be subsequently derivatized, either into an imine by protonation of the ketenimine moiety, or into a neutral ketenimine by alkylation of the intracyclic malonate moiety. Further experiments on the electrophilic behavior of [1]·Li revealed its unexpected reactivity toward p-chlorobenzaldehyde, resulting in a formal C-H activation and the first structurally characterized keto-tautomer of the Breslow intermediate. Finally, [1]·Li remarkably activates polar E-H bonds, including N-H bonds from ammonia and amines, Si-H bonds, and B-H bonds. Importantly, DFT calculations indicate the importance of counterion effects. In particular, the key to the observed reactivity appears to be a modulation of energy levels associated with a dynamic variability of the Li-O distance between the remote malonate group and the counterion.

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“…To our surprise, analogous species 1 B−E,R exist as true intermediates in the energy surface, and apart from 1 R , we surmise that the influence of a single lone-pair-containing substituent might play a role for their existence (Figures S2− S7). It is important to mention about recent experimental evidence regarding isolation and characterization of similar N 2 O adducts with various substituted N-heterocyclic carbenes by Severin et al 117,118 Existence of silanone, in general, as a transient species eludes its isolation and further characterization. The high reactivity of silanone is attributed to the strongly polarized SiO bond, which is considered to have zwitterionic character with an electron deficient Si + center and a negatively charged oxygen atom.…”

Section: Resultsmentioning

confidence: 99%

Computational Investigation on the Role of Disilene Substituents Toward N₂O Activation

Maity

Koley

2016

J. Phys. Chem. A

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The effect of substituents in disilene mediated NO activation was studied at the M06-2X/QZVP//ωB97xD/TZVP level of theory. The relationship between structural diversity and the corresponding reactivity of six disilenes (I) in the presence of four different substituents (-NMe, -Cl, -Me, -SiMe) is addressed in this investigation. We primarily propose two plausible mechanistic routes: Pathway I featuring disilene → silylene decomposition followed by NO coordination and Pathway II constituting the NO attack without Si-Si bond cleavage. Depending on the fashion of NO approach the latter route was further differentiated into Pathway IIa and Pathway IIb detailing the "end-on" and "side-on" attack to the disilene scaffold. Interestingly, the lone pair containing substituents (-NMe, -Cl,) facilitates disilene → silylene dissociation; on the contrary it reduces the electrophilicity at Si center in silylene, a feature manifested with higher activation barrier during NO attack. In the absence of any lone-pair influence from substituents (-Me, -SiMe), the decomposition of disilenes is considerably endothermic. Therefore, Pathway I appears to be the less preferred route for both types of substituents. In Pathway IIa, the NO moiety uniformly approaches via O-end to both the silicon centers in disilenes. However, the calculations reveal that Pathway IIa, although not operational for all disilenes, is unlikely to be a viable route due to the predominantly higher transition barrier (ca. 36 kcal/mol). The most feasible route in this current study accompanying moderately low activation barriers (∼19-26 kcal/mol) is Pathway IIb, which involves successive addition of two NO units proceeding via terminal N, O toward the Si centers and is applicable for all disilenes. The reactivity of substituted disilenes can be estimated in terms of the first activation barrier of NO attack. Surprisingly, in Pathway IIb, the initial activation barrier and hence the reactivity shows negligible correlation with Si-Si bond strength, indicating toward the versatility of the reaction route.

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Covalent Capture of Nitrous Oxide by N‐Heterocyclic Carbenes

Abstract: Ein guter Fang: N‐heterocyclische Carbene (NHCs) bilden unter milden Reaktionsbedingungen stabile Addukte mit Distickstoffoxid (N2O). Die Addukte zeigen eine ungewöhnliche Reaktivität, wie am Beispiel einer Alkylierungsreaktion unter Spaltung der N‐N‐Bindung zu sehen ist.

Cited by 76 publications

References 46 publications

Synthesis of a “Masked” Terminal Nickel(II) Sulfide by Reductive Deprotection and its Reaction with Nitrous Oxide

Synthesis of a “Masked” Terminal Nickel(II) Sulfide by Reductive Deprotection and its Reaction with Nitrous Oxide

The Ambivalent Chemistry of a Free Anionic N‐Heterocyclic Carbene Decorated with a Malonate Backbone: The Plus of a Negative Charge

Computational Investigation on the Role of Disilene Substituents Toward N₂O Activation

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Covalent Capture of Nitrous Oxide by N‐Heterocyclic Carbenes

Abstract: Ein guter Fang: N‐heterocyclische Carbene (NHCs) bilden unter milden Reaktionsbedingungen stabile Addukte mit Distickstoffoxid (N2O). Die Addukte zeigen eine ungewöhnliche Reaktivität, wie am Beispiel einer Alkylierungsreaktion unter Spaltung der N‐N‐Bindung zu sehen ist.

Cited by 76 publications

References 46 publications

Synthesis of a “Masked” Terminal Nickel(II) Sulfide by Reductive Deprotection and its Reaction with Nitrous Oxide

Synthesis of a “Masked” Terminal Nickel(II) Sulfide by Reductive Deprotection and its Reaction with Nitrous Oxide

The Ambivalent Chemistry of a Free Anionic N‐Heterocyclic Carbene Decorated with a Malonate Backbone: The Plus of a Negative Charge

Computational Investigation on the Role of Disilene Substituents Toward N2O Activation

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Computational Investigation on the Role of Disilene Substituents Toward N₂O Activation